FIX bootloop || TWRP Error || Flashing Stock ROM || SOLVED Samsung A12

Download Stock Rom
https://www.sammobile.com/

Download Tool Odin 3.14.1
https://odin-samsung.com/odin-3-14-1-...

Bootloops occur due to multiple reasons, so the best way to fix them is to find the specific thing that caused it and solving it, for example flashing ViPER4Android Fx can cause bootloop in android 10, but if you delete the post-fs script using your TWRP recovery, the problem is solved. A lot of things can be fixed in a similar way.
If you had a custom ROM try reflashing that ROM(dirty flash it or you’ll loose the existing app data and stuff). This is especially solves the problem created by custom kernels. If dirty flash doesn’t solve it go for clean flashing your ROM, this should solve most of the problems. You could also try factory reset.
The all-fix for bootloop is flashing the stock rom or restoring your nandroid backup, because these stuff are sure to function normally on your phone.